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Origins of life (featuring Dr. Katrine Whiteson) · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: How do you go from a barren planet being bombarded
• 0:10
  Speaker 1: with asteroids to a planet that, over four billion plus years,
• 0:14
  Speaker 1: has been home to what is probably billions of species.
• 0:18
  Speaker 1: This is Daniel and Kelly's Extraordinary Universe, so you're not
• 0:21
  Speaker 1: going to be surprised to learn that we're not one
• 0:23
  Speaker 1: hundred percent sure yet, but as this is one of
• 0:25
  Speaker 1: the most profound questions humans can ask, scientists have certainly
• 0:29
  Speaker 1: been working on it.
• 0:30
  Speaker 2: So on today's show, we're going to.
• 0:32
  Speaker 1: Talk about what we know so far about the origins
• 0:34
  Speaker 1: of life. Welcome to Daniel and Kelly's Extraordinary Universe.
• 0:52
  Speaker 3: Hi. I'm Daniel.
• 0:53
  Speaker 4: I'm a particle physicist who likes to think about aliens,
• 0:56
  Speaker 4: and I consider the origin of life to be sort
• 0:59
  Speaker 4: of the Big Bang of biology.
• 1:01
  Speaker 2: Oh hello, I'm Kelly.
• 1:02
  Speaker 1: I study parasites and space and go ahead elaborate. Why
• 1:06
  Speaker 1: is ool origins of life analogous to the Big Bang?
• 1:11
  Speaker 4: Because it's so important, it's so mysterious, it's not widely
• 1:15
  Speaker 4: understood by scientists in the sense that it's still, you know,
• 1:19
  Speaker 4: an open question, and how much we don't understand about
• 1:22
  Speaker 4: it is deeply misunderstood by the public.
• 1:25
  Speaker 1: Yeah, yeah, I learned so much when I was researching
• 1:28
  Speaker 1: this episode, so I would definitely agree with you. This
• 1:31
  Speaker 1: was quite a journey to go on, and it's a
• 1:33
  Speaker 1: journey that a bunch of our listeners have wanted us
• 1:35
  Speaker 1: to go on for a while. So we've gotten a
• 1:37
  Speaker 1: lot of requests for early life episodes. When you study
• 1:41
  Speaker 1: early life, that sounds like a biology question, But it's
• 1:45
  Speaker 1: a chemistry question, guys.
• 1:47
  Speaker 2: It's a chemistry question.
• 1:48
  Speaker 1: So I've been trying to avoid this for a while,
• 1:52
  Speaker 1: but I could put it off no longer because it
• 1:54
  Speaker 1: is actually a fascinating topic.
• 1:56
  Speaker 4: And turns out chemistry is kind of unavoidable.
• 1:58
  Speaker 2: Yeah, that's right.
• 1:59
  Speaker 1: So so hat tip to Jeff for asking us for
• 2:02
  Speaker 1: episodes on early life, and to Frank who suggested that
• 2:05
  Speaker 1: I check out doctor Nick Lane's work. He wrote a
• 2:07
  Speaker 1: great book called The Vital Question, for example, and I
• 2:10
  Speaker 1: did read that.
• 2:11
  Speaker 4: And because neither of us are chemists, but I'm married
• 2:14
  Speaker 4: to somebody who has a PhD in biochemistry, we decided
• 2:17
  Speaker 4: to bring on the podcast our favorite pinch hitter.
• 2:20
  Speaker 1: Yay, So let's waste no time because nobody really wants
• 2:24
  Speaker 1: to hear you and I talk when they could hear
• 2:25
  Speaker 1: Katrina talk so let's bring Katrina on the show.
• 2:28
  Speaker 4: Okay, then it's my pleasure again to welcome back to
• 2:31
  Speaker 4: the podcast our favorite guest, or maybe co host, Katrina Whitson,
• 2:37
  Speaker 4: Director of the Whites and Institute Center for Fermented Beverages
• 2:40
  Speaker 4: of Dubious Safety. Katrina, Welcome back to the podcast.
• 2:44
  Speaker 5: Wow, these interests have taken a very interesting turn. But
• 2:48
  Speaker 5: I just want to say I'm way more of a
• 2:49
  Speaker 5: sidekick on this one. This is not something where you know,
• 2:53
  Speaker 5: I've spent a lifetime learning, but it's something I'm very
• 2:56
  Speaker 5: interested in. So I'm glad we're going to get to
• 2:58
  Speaker 5: talk about it.
• 2:58
  Speaker 4: Well, we're always very happy to have your my crobial
• 3:00
  Speaker 4: expertise on these questions.
• 3:02
  Speaker 1: And a lot of this stuff is philosophical and so
• 3:04
  Speaker 1: just having another, you know, fun person to bounce philosophical
• 3:07
  Speaker 1: ideas off of is good.
• 3:08
  Speaker 2: And Daniel, are.
• 3:09
  Speaker 1: You ever gonna move past this kombucha thing? Because it
• 3:13
  Speaker 1: feels like it's living rent free in your head and
• 3:16
  Speaker 1: we hear about it all the time.
• 3:19
  Speaker 4: When she turns into a billion dollar business.
• 3:22
  Speaker 5: I'll accept it, all right, Well that did happen here
• 3:25
  Speaker 5: in so Kyle, but I doubt that's going to be
• 3:26
  Speaker 5: my life plan. There was a guy, the GT Kombucha.
• 3:30
  Speaker 4: Guy Katrina's Crunchy Kombucha. Oh wait, no, that's a terrible acronym.
• 3:35
  Speaker 2: No, no, no, yep.
• 3:37
  Speaker 1: So let's run away from this conversation and into another
• 3:41
  Speaker 1: conversation that's a bit safer.
• 3:43
  Speaker 2: So how about what is life?
• 3:45
  Speaker 1: So you know, when you're trying to figure out where
• 3:47
  Speaker 1: life came from, what you need is a definition so
• 3:51
  Speaker 1: that when you see a thing, you can say, Okay.
• 3:53
  Speaker 2: That's that's life. And so that's what we're working towards.
• 3:55
  Speaker 1: And it would be helpful if you had a definition
• 3:57
  Speaker 1: for life that worked tire or anywhere else in the universe.
• 4:01
  Speaker 1: But we're kind of constrained to what we know is
• 4:04
  Speaker 1: happening here, and so what we've observed happening on Earth.
• 4:09
  Speaker 1: Here are some features of life on Earth that can
• 4:11
  Speaker 1: sort of get the ball rolling. One of those features
• 4:14
  Speaker 1: is that it's carbon based. And we did a whole
• 4:17
  Speaker 1: listener question on why we think it's carbon as opposed
• 4:20
  Speaker 1: to something like silicon silicone.
• 4:22
  Speaker 2: Silicon silicone is different, Yeah, that's right, that's right. Silicon.
• 4:28
  Speaker 1: It depends on water and information is carried in DNA
• 4:34
  Speaker 1: or RNA and so it's genetic. We used to think
• 4:37
  Speaker 1: that you also had to get energy from the sun,
• 4:40
  Speaker 1: either directly or indirectly by like eating plants that got
• 4:43
  Speaker 1: energy from the sun. But in like the seventies, we
• 4:46
  Speaker 1: discovered that you can get energy from hydrothermal vents. So
• 4:49
  Speaker 1: even in the last you know, fifty sixty years, we've
• 4:51
  Speaker 1: been like changing our definition of what we think life is.
• 4:54
  Speaker 1: So is there anything you too would add to like
• 4:57
  Speaker 1: features of life on Earth?
• 5:00
  Speaker 4: It's a pretty good list, but I want to highlight
• 5:02
  Speaker 4: the difference between features of life on Earth and what
• 5:05
  Speaker 4: we think life is because we're interested in this question
• 5:09
  Speaker 4: what is life? Because we're also curious about like where
• 5:12
  Speaker 4: is life and how common is life? And so we're
• 5:14
  Speaker 4: interested in, like is there life on Enceladus or you know,
• 5:17
  Speaker 4: on that other planet, And we don't necessarily expect it
• 5:20
  Speaker 4: to have all these features, but it's really important to
• 5:23
  Speaker 4: have a definition so that when we do see it,
• 5:25
  Speaker 4: we're like, well, is it life? And also so we
• 5:28
  Speaker 4: can like have a conversation because you know, every good
• 5:31
  Speaker 4: philosophy conversation starts with the definition, so you make sure
• 5:34
  Speaker 4: you're at least talking about the same thing and not
• 5:37
  Speaker 4: discovering you know fifty pages later that you're having two
• 5:40
  Speaker 4: different arguments.
• 5:41
  Speaker 1: So do you really think that this is a situation
• 5:43
  Speaker 1: where we need to have a definition? Because I was
• 5:45
  Speaker 1: listening to an interview with Nick Lane, who's a guy
• 5:48
  Speaker 1: who does a bunch of work on this, and it
• 5:50
  Speaker 1: was actually he was on Brian Keating show and Brian
• 5:53
  Speaker 1: Keating asked, how, like what is life? How would you
• 5:55
  Speaker 1: define it? And he said, well, I can't tell you.
• 5:58
  Speaker 1: It's one of those funny questions. If you get an
• 6:00
  Speaker 1: answer from someone, it'll be a bad answer. And then
• 6:03
  Speaker 1: later he actually referred to coming up with the definition
• 6:07
  Speaker 1: as quote actively unhelpful. And so what do you do?
• 6:13
  Speaker 1: Does a definition hamstring us? Because we like, especially if
• 6:17
  Speaker 1: you're searching for life out in the universe, it might
• 6:19
  Speaker 1: be totally outside of.
• 6:21
  Speaker 2: What we're familiar with. So how important do you think
• 6:24
  Speaker 2: a definition is?
• 6:25
  Speaker 5: I mean, I have to say I find the definition
• 6:28
  Speaker 5: thing a little boring, if not unhelpful, and I'm.
• 6:32
  Speaker 2: Glad we're starting with it, yes.
• 6:34
  Speaker 5: Because so for you know, I've studied viruses a lot,
• 6:39
  Speaker 5: and viruses are always there's this debate about whether they're
• 6:43
  Speaker 5: alive or not, and it's something that you teach in
• 6:46
  Speaker 5: every virology class, and I honestly, I just I can't
• 6:50
  Speaker 5: get excited about that debate. I'm not exactly sure why.
• 6:53
  Speaker 5: I guess I just feel like we understand how the
• 6:55
  Speaker 5: viruses work. We know in what ways they fail the
• 6:58
  Speaker 5: definition that you just brought up, which is that they
• 7:00
  Speaker 5: are not able to replicate by themselves. They have to
• 7:02
  Speaker 5: go borrow a host cell. It's like, you know, if
• 7:05
  Speaker 5: you rent an Airbnb, you're not going to bring a
• 7:08
  Speaker 5: washing machine, You're just going to borrow the one that's there.
• 7:10
  Speaker 5: And that's what viruses do. But they have a program,
• 7:13
  Speaker 5: they know what they're doing, and they also are probably
• 7:17
  Speaker 5: the most diverse entity on the planet when it comes
• 7:21
  Speaker 5: to biology. They are like rocking it in terms of
• 7:24
  Speaker 5: what information they create because they are so diverse, and
• 7:29
  Speaker 5: so to leave them out of the definition of life
• 7:31
  Speaker 5: just never made any sense to me.
• 7:33
  Speaker 4: I mean, if you landed on an alien planet and
• 7:34
  Speaker 4: only found viruses, you wouldn't be like, yawn, I guess
• 7:38
  Speaker 4: this place is.
• 7:39
  Speaker 5: Boring, right, No, definitely not. But if I only saw viruses,
• 7:43
  Speaker 5: I would think, oh, this is like a weird shadow
• 7:45
  Speaker 5: of something that happened somewhere else, or they killed all
• 7:48
  Speaker 5: the cells, I guess, because that's not a stable system
• 7:51
  Speaker 5: that is actually able to sustain life. So I mean,
• 7:54
  Speaker 5: in that sense the definition matters, of course, because you know,
• 7:58
  Speaker 5: viruses can't do that by themselves.
• 8:00
  Speaker 1: Can I ask you a question that I absolutely should
• 8:02
  Speaker 1: know the answer to, but I don't. So okay, So
• 8:05
  Speaker 1: people always say, you know, like life arose once, and
• 8:08
  Speaker 1: so I don't usually think about where viruses are on
• 8:11
  Speaker 1: the tree of life. Did viruses arise separate from bacteria?
• 8:15
  Speaker 1: Are Chia and eu carryoutes or did they branch off
• 8:18
  Speaker 1: at one point?
• 8:20
  Speaker 2: Do we know? I think they got.
• 8:21
  Speaker 5: There first, and I hear this whole only evolved one's thing.
• 8:25
  Speaker 5: But I mean, I don't think we really know that
• 8:27
  Speaker 5: we know what we have now. Yeah, I think it's possible.
• 8:32
  Speaker 5: I mean, whatever happened in the very very beginning was
• 8:35
  Speaker 5: probably you know, this biochemical soup, and there were probably
• 8:41
  Speaker 5: little self replicating genetic entities going on there which were
• 8:45
  Speaker 5: not yet cells, and we're also not yet viruses. But
• 8:49
  Speaker 5: I would say that as soon as we had any
• 8:51
  Speaker 5: kind of successful entity going there were quickly genetic parasites,
• 8:57
  Speaker 5: which in a way are akin to virus ruses. I
• 9:01
  Speaker 5: think that probably started very early, if not right away.
• 9:04
  Speaker 5: I mean I think the second there was something good
• 9:06
  Speaker 5: going on, there were like hitchhikers jumping in.
• 9:09
  Speaker 4: You know, you're totally pandering to Kelly with genetic parasites.
• 9:13
  Speaker 2: Nice.
• 9:14
  Speaker 1: Yeah, I say the same thing to people, and I
• 9:16
  Speaker 1: was like, no, I don't know this for sure, but
• 9:17
  Speaker 1: I'm so glad that a very smart persons the same thing.
• 9:20
  Speaker 2: Now I feel very confident.
• 9:22
  Speaker 4: But I think it is important that we have a definition,
• 9:24
  Speaker 4: even if there are fascinating things that fall outside of it, right,
• 9:28
  Speaker 4: And like, I have nothing against airbnb guests and it's wonderful. Yeah,
• 9:32
  Speaker 4: and I'm a guest myself. I hope the viruses clean
• 9:35
  Speaker 4: up after themselves and don't you know bother the neighbors
• 9:37
  Speaker 4: and all that time, they're not very constrained. But I
• 9:43
  Speaker 4: do think we want to sharpen the question. We want
• 9:45
  Speaker 4: to know what we're talking about. I don't care people
• 9:49
  Speaker 4: agree when we find aliens, whether it's life or not,
• 9:53
  Speaker 4: but we're interested in the questions. We have to, like,
• 9:55
  Speaker 4: at least know what we're talking about. Why is this
• 9:58
  Speaker 4: question interesting? And maybe continuing saying it's a spectrum and
• 10:02
  Speaker 4: there's you know, a blend of stuff, and you can
• 10:04
  Speaker 4: call it life or not. But you know, there's an
• 10:07
  Speaker 4: interesting into it, and there's a non interesting into it,
• 10:09
  Speaker 4: like you know, rocks, like basically everything we've only found
• 10:12
  Speaker 4: so far. But I think we at least need to
• 10:15
  Speaker 4: identify the direction of that interestingness so that even if
• 10:19
  Speaker 4: we aren't sure where the threshold is, we can say, like, oh,
• 10:21
  Speaker 4: look what.
• 10:22
  Speaker 3: We found here.
• 10:22
  Speaker 4: This is fascinating and it's similar in some respects to
• 10:25
  Speaker 4: what we're doing over here on Earth.
• 10:27
  Speaker 1: Well, so then let's let's go through a couple definitions
• 10:30
  Speaker 1: that I've identified. Know that Katrina has told us this
• 10:33
  Speaker 1: is not an interesting question, let's dwell on it.
• 10:37
  Speaker 4: Let's dig into the boring question of what is life.
• 10:40
  Speaker 2: I'm just kidding. I got to pick on you too sometimes, Yeah,
• 10:44
  Speaker 2: you can just yes, no, okay.
• 10:49
  Speaker 1: So Irwin Schroedinger in nineteen forty four said that life is.
• 10:53
  Speaker 2: A thing that famous biologist I thought he was a physicist.
• 10:56
  Speaker 3: Yes, exactly, that's the joke.
• 11:00
  Speaker 1: Well, I was starting with a not so good definition,
• 11:02
  Speaker 1: so I wanted to I'm going after bulls of the
• 11:07
  Speaker 1: whites and today.
• 11:08
  Speaker 2: All right, so life is.
• 11:09
  Speaker 1: A thing that avoids the decay into equilibrium, and so
• 11:13
  Speaker 1: I feel like this focuses on metabolism because you need
• 11:16
  Speaker 1: metabolism to like push against the decay into equilibrium.
• 11:19
  Speaker 2: But what do you think of that definition?
• 11:22
  Speaker 5: I think it works both in a metabolism way and
• 11:26
  Speaker 5: in an information way, information being more about the genetic
• 11:30
  Speaker 5: organization where we store our information. I mean that is
• 11:33
  Speaker 5: the opposite of just like a total neutral chaos where
• 11:35
  Speaker 5: there's no organization. So I think that kind of works.
• 11:39
  Speaker 5: I don't know, does that help us when we send
• 11:40
  Speaker 5: a mass back up to Mars and look for molecules
• 11:44
  Speaker 5: and we're like, does this tell us that something was
• 11:46
  Speaker 5: alive here? I'm not sure, because those things could happen
• 11:49
  Speaker 5: randomly here or there, and you would need to see
• 11:52
  Speaker 5: like interesting concentrations of things maybe, But even then, I
• 11:55
  Speaker 5: don't know. That's where the definition gets helpful. I see
• 11:58
  Speaker 5: what you're saying.
• 11:59
  Speaker 4: No disrespect the of course, but I think that's interesting,
• 12:03
  Speaker 4: but I'm not sure it captures everything like that. You
• 12:05
  Speaker 4: could also, for example, build a robot like a rumba is,
• 12:09
  Speaker 4: you know, organizing and cleaning and fighting against entropy and stuff.
• 12:13
  Speaker 4: But nowbody would say a rumba is alive, and so
• 12:16
  Speaker 4: maybe I don't know the metabolic aspect of it, there
• 12:19
  Speaker 4: would disqualifier rumba. I think it's getting at something, you know,
• 12:23
  Speaker 4: it's capturing the sense that life is self maintaining. It's
• 12:27
  Speaker 4: fighting against you know, the laws of thromodynamics.
• 12:30
  Speaker 5: Yeah, but the rumba will eventually disintegrate. I mean, I
• 12:33
  Speaker 5: don't know the details about the plastics in there, but
• 12:35
  Speaker 5: you know what I'm saying, it's not going to be
• 12:37
  Speaker 5: able to sustain that over generations.
• 12:40
  Speaker 1: But so well, we we're going to disintegrate. Is it
• 12:43
  Speaker 1: that the rumba doesn't make babies? That's the Yeah? What
• 12:46
  Speaker 1: what did you what were you thinking of in particular
• 12:49
  Speaker 1: that like the plastic is going to fall apart, Because
• 12:50
  Speaker 1: I'm falling apart pretty quicklyly.
• 12:52
  Speaker 2: It feels like, well.
• 12:54
  Speaker 5: I guess I was saying there might be something that
• 12:57
  Speaker 5: is still organized in a way that it wasn't there
• 13:00
  Speaker 5: before the room, but it was manufactured eons from now,
• 13:03
  Speaker 5: despite the fact that they won't have progeny. Okay, But
• 13:06
  Speaker 5: I guess I was, Yeah, I was saying it wasn't
• 13:08
  Speaker 5: sustainable because they won't reproduce.
• 13:10
  Speaker 2: Okay.
• 13:11
  Speaker 1: I feel like Katrina was mentioning that this is like
• 13:14
  Speaker 1: not super helpful, because how what do you do with this?
• 13:17
  Speaker 1: Like if you go to Mars, what are you looking for?
• 13:20
  Speaker 1: In particular? From this definition? It doesn't really tell you that.
• 13:23
  Speaker 1: It's kind of like too vague to be helpful, I
• 13:26
  Speaker 1: guess is my thought. But this was from you know,
• 13:28
  Speaker 1: like eighty years ago, right, and so we've got some
• 13:30
  Speaker 1: other definitions to chat about.
• 13:32
  Speaker 5: And that was before we knew DNA. I mean, that
• 13:34
  Speaker 5: was a really early moment. Yeah, thinking about that.
• 13:37
  Speaker 1: Yeah, that's a good point. That's a good way we
• 13:39
  Speaker 1: shouldn't be too harsh on Schroeder. Yeah, it was a pioneer.
• 13:43
  Speaker 1: So in nineteen ninety four, NASA had a working group
• 13:46
  Speaker 1: and they came up with a definition. And their definition
• 13:50
  Speaker 1: is that life is a self sustaining chemical system capable
• 13:53
  Speaker 1: of Darwinian evolution. That's a little more specific, So self sustaining,
• 14:00
  Speaker 1: like it's its own entity, it can acquire its own
• 14:02
  Speaker 1: food and like keep itself going. It's a chemical system
• 14:06
  Speaker 1: and undergoes Darwinian evolution. So like DNA is sort of
• 14:09
  Speaker 1: implied in there, or at least some information that gets
• 14:12
  Speaker 1: passed from generation to generation, and like reflex changes that
• 14:17
  Speaker 1: are happening over time. So this is like, at least
• 14:20
  Speaker 1: a little bit more specific. What do you all think
• 14:21
  Speaker 1: of this one?
• 14:22
  Speaker 4: I like that it's more specific. It also seems more descriptive, though,
• 14:26
  Speaker 4: right it doesn't feel like it's unearthing a core concept here.
• 14:32
  Speaker 4: It's just like, what is life having in common? And
• 14:35
  Speaker 4: I think that's a step towards it.
• 14:36
  Speaker 3: Right.
• 14:36
  Speaker 4: It's like you start out with a bunch of observations
• 14:39
  Speaker 4: and then later you understand the underlying concepts that are
• 14:43
  Speaker 4: unifying it all. And we're not there yet. We're still
• 14:46
  Speaker 4: just like understand the pieces, you know. It's like when
• 14:49
  Speaker 4: we saw magnets and we saw lightning, we did realize, oh,
• 14:52
  Speaker 4: these are two sides of the same coin, and there's
• 14:54
  Speaker 4: a reason why they both come from the same thing.
• 14:57
  Speaker 4: So I feel like we're sort of at that stage here.
• 14:59
  Speaker 4: We're like making lists without understanding where they come from.
• 15:03
  Speaker 1: Well, I've got another list to throw at you, and
• 15:04
  Speaker 1: then we can move on to something more interesting. So
• 15:06
  Speaker 1: the last definition that I found was a definition that's
• 15:10
  Speaker 1: sometimes called the Seven Pillars of Life. It's came out
• 15:15
  Speaker 1: of UC Berkeley in two thousand and two. Daniel, when
• 15:17
  Speaker 1: were you at Berkeley.
• 15:18
  Speaker 4: I was Berkeley ninety eight to two thousand, and that
• 15:20
  Speaker 4: was a Fermi lab while still a Berkeley student until
• 15:22
  Speaker 4: two thousand and three.
• 15:24
  Speaker 1: Okay, so you were there, Well, Daniel Koshland was working
• 15:28
  Speaker 1: on this.
• 15:28
  Speaker 5: Oh yeah, we had. I studied biology at Berkeley ninety
• 15:32
  Speaker 5: six to two thousand and one of our buildings was
• 15:34
  Speaker 5: named Koshlin. So that's interesting.
• 15:36
  Speaker 1: Oh fantastic. Okay, all right, Well, so here we go.
• 15:39
  Speaker 1: Here are the seven pillars. One pillar is program and
• 15:43
  Speaker 1: for us that's DNA. It's the thing that sort of
• 15:46
  Speaker 1: like carries the instructions for life. And then you've got improvisation,
• 15:51
  Speaker 1: and this I think is meant to cover like natural selection.
• 15:55
  Speaker 1: Improvisation doesn't feel quite like the right word to use for.
• 15:58
  Speaker 5: That, yeah, because that's it's just like mutants arise and
• 16:01
  Speaker 5: then the best ones arrives. That's not like on the spot,
• 16:04
  Speaker 5: they like invented a new thing. That's interesting, right Yeah.
• 16:07
  Speaker 1: Yeah, So I'm not loving the word, but I get
• 16:09
  Speaker 1: that The point is they're like things that change through
• 16:12
  Speaker 1: natural selection.
• 16:13
  Speaker 5: Yeah, like a roomba couldn't do that.
• 16:14
  Speaker 1: Right, Yeah, Yeah, Ruma's going to be our go to thing.
• 16:17
  Speaker 1: I can see now compartmentalization, so like it's not just
• 16:22
  Speaker 1: like part of an ooze. It sort of separates itself
• 16:24
  Speaker 1: from the rest of the environment in some way, like
• 16:27
  Speaker 1: you know, often a lipid bilayer is how cells do that.
• 16:30
  Speaker 1: They separate themselves from other cells energy, so they take
• 16:34
  Speaker 1: in energy and use that energy to do things like
• 16:38
  Speaker 1: replicate themselves. Regeneration and this is things like growing the
• 16:43
  Speaker 1: size of your population, having babies, Healing covers a lot
• 16:47
  Speaker 1: of things. Adaptability, so this is adapting to like responding
• 16:52
  Speaker 1: to your environment. Adaptability felt like that's the word I
• 16:56
  Speaker 1: associate with natural selection. It's kind of I'm still stuck
• 16:58
  Speaker 1: on improvisation, not feeling a good word.
• 17:00
  Speaker 5: Yeah, those are interesting sides of the same coin. I
• 17:03
  Speaker 5: don't quite get the difference. I have to think about that.
• 17:06
  Speaker 1: I bet this person was a physicist. And then seclusion,
• 17:11
  Speaker 1: which is like having your own chemical processes that are
• 17:14
  Speaker 1: going on inside of you. And so now I'm not
• 17:16
  Speaker 1: sure what the difference between seclusion and compartmentalization are. But anyway,
• 17:20
  Speaker 1: so I feel like there's some redundancies in here as
• 17:24
  Speaker 1: I understood the definition, and a couple words that maybe
• 17:26
  Speaker 1: I wouldn't have picked.
• 17:27
  Speaker 2: But with these letters.
• 17:29
  Speaker 1: You can have the acronym picarus or piscerius, and I
• 17:32
  Speaker 1: don't know, maybe they were going for that, but how do.
• 17:34
  Speaker 2: Those feel as criteria for life?
• 17:37
  Speaker 1: So, Daniel, this is getting a little more specific, but
• 17:40
  Speaker 1: I really know if it's a theory as opposed to
• 17:42
  Speaker 1: like a summary of observations, it's.
• 17:44
  Speaker 4: Still a summary of observations, and I feel like it's
• 17:46
  Speaker 4: too biased towards the kind of things we see here
• 17:49
  Speaker 4: on Earth. I'm especially not a fan of this compartmentalization
• 17:54
  Speaker 4: and seclusion business. I feel like that's not even very
• 17:57
  Speaker 4: well defined, Like where exactly does my and anyway is
• 18:02
  Speaker 4: not very clear, Like I have a surface covered with microbes,
• 18:05
  Speaker 4: Are they part of me?
• 18:06
  Speaker 3: Are they not part of me?
• 18:08
  Speaker 4: I feel like that's just a cultural framework we're imposing
• 18:13
  Speaker 4: on even Earth biology where it doesn't really work. And
• 18:17
  Speaker 4: I can imagine situations where you have life that doesn't
• 18:21
  Speaker 4: have clear boundaries, but you would still understand it to
• 18:24
  Speaker 4: be life, and then they might think of themselves differently.
• 18:27
  Speaker 4: And you know, we've talked about this on the podcast before,
• 18:30
  Speaker 4: like plasma currents in the atmosphere of a star could
• 18:33
  Speaker 4: be self sustaining and interesting and even intelligent but they
• 18:38
  Speaker 4: might not have the concept of like counting numbers if
• 18:41
  Speaker 4: they don't have like boundaries between their bodies and other
• 18:44
  Speaker 4: people's bodies, and so they might like just think in
• 18:47
  Speaker 4: real numbers instead of integers. And so this feels like
• 18:50
  Speaker 4: a little too earth centric to me. But again, it's
• 18:53
  Speaker 4: it's like a list. It's a description of what we
• 18:56
  Speaker 4: see on Earth, which is mostly accurate. And I think
• 18:59
  Speaker 4: the next big leap would be, like, let's understand the
• 19:02
  Speaker 4: core concepts. But it doesn't seem like we're there yet.
• 19:04
  Speaker 1: Sounds like Kashlin needed to smoke some banana peels. I
• 19:07
  Speaker 1: have a ba broader view of things, and while you
• 19:11
  Speaker 1: were talking, I was one totally listening, but two I
• 19:14
  Speaker 1: also looked up seclusion and compartmentalization again to see what
• 19:18
  Speaker 1: I was getting wrong. And it looks like maybe seclusion
• 19:21
  Speaker 1: is more about like stuff that's happening intracellularly and anyway.
• 19:25
  Speaker 1: But still the point is sort of like separation of stuff.
• 19:28
  Speaker 1: So your point still stands, all right, Well, I think
• 19:32
  Speaker 1: we have had enough of a chat about this. The
• 19:34
  Speaker 1: point is people are trying to identify things that are
• 19:38
  Speaker 1: important for life. Here are thinking about what might be
• 19:40
  Speaker 1: important for life and other places in the universe. But
• 19:43
  Speaker 1: at the end of the day, we've only seen what
• 19:45
  Speaker 1: has succeeded here on Earth. And as Katrina was alluding
• 19:48
  Speaker 1: to earlier, life could have popped up multiple times, but
• 19:52
  Speaker 1: there was like one instance that gave rise. There was
• 19:54
  Speaker 1: one instance we think that gave rise to everything that
• 19:56
  Speaker 1: we see today. But maybe life popped up and then
• 19:59
  Speaker 1: just kind of died, and so we don't really know
• 20:01
  Speaker 1: what the other options could have been. And so anyway,
• 20:04
  Speaker 1: we are going to plow forward in our conversation without
• 20:08
  Speaker 1: a definition that everybody agrees on, because this is biology
• 20:12
  Speaker 1: and that is what we do.
• 20:14
  Speaker 4: If this was philosophy, we would just stay here for
• 20:16
  Speaker 4: four hundred years arguing.
• 20:17
  Speaker 2: About that's right, that's right.
• 20:20
  Speaker 1: The good news is that there have been a lot
• 20:21
  Speaker 1: of experiments and that we are moving forward despite having
• 20:24
  Speaker 1: a definition, towards trying to get something life like happening
• 20:28
  Speaker 1: in the lab. So let's take a break and when
• 20:30
  Speaker 1: we get back, we'll talk about when we think life
• 20:34
  Speaker 1: arose and what Earth was kind of like at that time,
• 20:37
  Speaker 1: so that we can ground our experiments in something sort
• 20:41
  Speaker 1: of reasonable.
• 21:01
  Speaker 4: All right, we're back. We're talking about what is life?
• 21:04
  Speaker 4: The origins of life and we're trying to keep Katrina
• 21:06
  Speaker 4: from being too bored. Kelly, what are we talking about next?
• 21:10
  Speaker 1: Oh no, well the good news is we're talking about
• 21:12
  Speaker 1: bacteria related stuff.
• 21:14
  Speaker 2: So I think that's gonna Yeah, there we go. All right,
• 21:16
  Speaker 2: so I'm on track.
• 21:17
  Speaker 3: Now she's interested, folks.
• 21:19
  Speaker 2: That's right.
• 21:21
  Speaker 1: So if you're trying to figure out how life came
• 21:24
  Speaker 1: to be, you want to sort of know what the
• 21:27
  Speaker 1: environment was like when life started. And to do that,
• 21:31
  Speaker 1: you need to know when life started. And so basically
• 21:34
  Speaker 1: we have to go to the fossil record to try
• 21:35
  Speaker 1: to figure out where is the first evidence that we
• 21:38
  Speaker 1: see something that could be life showing up.
• 21:42
  Speaker 4: Also, this is like amazing fascinating history, right, like the
• 21:45
  Speaker 4: deep history of life on Earth, like how things began. Wow,
• 21:48
  Speaker 4: I would love to jump into time machine and see
• 21:50
  Speaker 4: all this stuff happen. And it's our history, right, and
• 21:53
  Speaker 4: it happened a certain way and there might be clues
• 21:55
  Speaker 4: that reveal it. So it's like some of the most
• 21:57
  Speaker 4: fascinating science there is in my opinion.
• 21:59
  Speaker 1: Yeah, yeah, I agree with you, physicist, because it's myology
• 22:03
  Speaker 1: that we're looking at.
• 22:05
  Speaker 2: Okay, so.
• 22:07
  Speaker 1: There's a bunch of fossils out there from varying time points,
• 22:12
  Speaker 1: and some of them we agree are definitely evidence of bacteria,
• 22:17
  Speaker 1: way more than we agree about some other stuff. So
• 22:19
  Speaker 1: the most widely agreed upon fossil as far as I
• 22:22
  Speaker 1: could tell, was from Australia, and it's stromatallites that are
• 22:27
  Speaker 1: three and a half billion years old.
• 22:29
  Speaker 5: Yeah.
• 22:29
  Speaker 2: Wow, about three and a half billion.
• 22:31
  Speaker 1: Yeah, And so Katrina, at this point I was hoping
• 22:33
  Speaker 1: I could throw to you and be like, what are stromatallites?
• 22:35
  Speaker 1: But I didn't prepare you for that at all.
• 22:38
  Speaker 5: So stromatolites are amazing evidence we think of life that's
• 22:44
  Speaker 5: three point five billion years old, and it comes from
• 22:48
  Speaker 5: microbial mats. We've talked about biofilms before, and so the
• 22:52
  Speaker 5: stromatolites are layered rock structures that built up over time
• 22:58
  Speaker 5: by microbial mats. We think they were primarily cyanobacteria, and
• 23:02
  Speaker 5: they change the shape of the rocks. This is like
• 23:04
  Speaker 5: a morphological piece of evidence. So they would trap sediment
• 23:08
  Speaker 5: and calcify the rock and they created this huge macroscopic
• 23:12
  Speaker 5: evidence of life on Earth. And it is a little
• 23:15
  Speaker 5: controversial because there's questions about whether that could have been
• 23:18
  Speaker 5: created by something that's not alive. But we think that biofilms,
• 23:23
  Speaker 5: essentially microbial mats of the cyanobacteria that did an ancient
• 23:28
  Speaker 5: form of photosynthesis. So they were getting energy from sunlight,
• 23:30
  Speaker 5: we think, and maybe also from some of the sediments
• 23:35
  Speaker 5: in the rocks, and they left behind massive changes in
• 23:40
  Speaker 5: the shapes of the rocks and that's why we think
• 23:42
  Speaker 5: there was life there.
• 23:43
  Speaker 3: Wow, what is it.
• 23:44
  Speaker 4: About these things that makes it convincing that there's no
• 23:46
  Speaker 4: abiotic way to reproduce them?
• 23:49
  Speaker 5: Well, we know what those look like in modern times,
• 23:52
  Speaker 5: and it really is the shape of the leftover calcified
• 23:56
  Speaker 5: sediment that happened in a massive scale, and so so
• 24:00
  Speaker 5: you know, it's a guess, you know, or that's maybe
• 24:03
  Speaker 5: the wrong.
• 24:03
  Speaker 3: Word, but it's an inference.
• 24:04
  Speaker 5: Yeah, it's just based on how they look. I don't
• 24:06
  Speaker 5: think we have like great other kinds of chemical physical evidence.
• 24:11
  Speaker 5: There is some some isotope ratio carbon isotope ratio evidence,
• 24:16
  Speaker 5: but you know that signal can be debated.
• 24:20
  Speaker 4: Also, they look really weird. There are these funny blobs
• 24:25
  Speaker 4: sitting in the ocean. Right, it's cool.
• 24:27
  Speaker 2: Gotta be aliens.
• 24:28
  Speaker 4: Yeah, aliens don't go with the conspiracy theories.
• 24:31
  Speaker 3: Come on.
• 24:33
  Speaker 2: To what I do, all right.
• 24:35
  Speaker 1: So in Australia, there's this stromatallite that is pretty broadly
• 24:38
  Speaker 1: agreed upon as like definitely being a stromatallite, and that
• 24:42
  Speaker 1: age is to about three and a half billion years old.
• 24:45
  Speaker 2: There's also some other.
• 24:47
  Speaker 1: Things that we found in like Canada, Greenland, some other
• 24:50
  Speaker 1: parts of the world that could age older something like
• 24:54
  Speaker 1: three point seven, maybe even up to four point two
• 24:57
  Speaker 1: billion years old, and so only older than what we've
• 25:00
  Speaker 1: seen in Australia. But all of these other instances are
• 25:03
  Speaker 1: things where people debate, like is that a strum matallite.
• 25:06
  Speaker 2: We're not really sure.
• 25:07
  Speaker 1: So we feel pretty good about this three and a
• 25:10
  Speaker 1: half billion year old date, but it could be even older.
• 25:14
  Speaker 2: It's just really hard to date stuff that's that old.
• 25:16
  Speaker 4: And you're saying three point seven and it might not
• 25:19
  Speaker 4: sound like a big difference, like three point five three
• 25:21
  Speaker 4: point seven, but that's two hundred million years. Remember it's
• 25:25
  Speaker 4: been sixty six million since the dinosaurs, so like two
• 25:28
  Speaker 4: hundred million years.
• 25:29
  Speaker 3: It is a long time. It's a lot of podcasts.
• 25:32
  Speaker 2: Yes, that's the best way to measure things.
• 25:34
  Speaker 1: When I was a kid, we used to measure things
• 25:36
  Speaker 1: in uh Ghostbuster episodes, but cartoon that was so I'd
• 25:41
  Speaker 1: ask my dad how many more Ghostbuster episodes?
• 25:43
  Speaker 2: Anyway?
• 25:44
  Speaker 1: Zero point two billion years is a lot of Ghostbuster episodes,
• 25:47
  Speaker 1: so exactly. So we're not totally sure. But now, Daniel,
• 25:50
  Speaker 1: I'm gonna put you on the spot. Oh boy, there's
• 25:53
  Speaker 1: a limit for how much we know about what the
• 25:56
  Speaker 1: early Earth was like, or even our ability to like
• 25:59
  Speaker 1: age the early and we usually have to go outside
• 26:02
  Speaker 1: of Earth to get these estimates for like how old
• 26:04
  Speaker 1: Earth is, For example, why is that, Daniel.
• 26:07
  Speaker 4: Well, the early Solar system was hot and nasty.
• 26:11
  Speaker 5: You know that sounds like a judgment.
• 26:12
  Speaker 4: Called I mean that only in a positive way.
• 26:18
  Speaker 2: This is getting too personal.
• 26:20
  Speaker 4: Move on, Like you know, somebody asks me, how's that
• 26:25
  Speaker 4: pasta sauce of it? Ooh, hot and nasty? That sounds
• 26:28
  Speaker 4: delicious anyway. So the early solar system, you know, collapses
• 26:34
  Speaker 4: from a big cloud of gas and you get the
• 26:36
  Speaker 4: Sun and then you have little other gravitational seeds that
• 26:39
  Speaker 4: coalesce heavier stuff to make like the Earth in a
• 26:43
  Speaker 4: rocky planets, and then the radiation from the Sun blows
• 26:46
  Speaker 4: off most of the gas and so you expose the
• 26:49
  Speaker 4: you know, heavier stuff silicon and carbon and all this
• 26:52
  Speaker 4: kind of stuff and oxygen that makes up the Earth.
• 26:54
  Speaker 4: But it's hot, and so you know, the rocks are
• 26:56
  Speaker 4: constantly being reformed and because of pressure with gravitational pressure,
• 27:02
  Speaker 4: so the early stuff is mostly destroyed. And so like
• 27:05
  Speaker 4: if you want to find out the age of the Earth,
• 27:07
  Speaker 4: you have to find like the age of the oldest rock.
• 27:10
  Speaker 4: But a lot of the rocks from the early days
• 27:12
  Speaker 4: had been remelted, right, they're gone. So that's why the
• 27:16
  Speaker 4: age of the Solar System is easiest to discover away
• 27:19
  Speaker 4: from the Earth and like asteroids, right, smaller chunks that
• 27:21
  Speaker 4: were still molten early but cooled and have been frozen
• 27:25
  Speaker 4: essentially ever since and have been like pushed down into
• 27:28
  Speaker 4: the Earth magma and melted.
• 27:30
  Speaker 2: Yeah awesome.
• 27:31
  Speaker 1: Yeah, And so there's a limit on what we can
• 27:32
  Speaker 1: even say about the early Earth because it doesn't really
• 27:35
  Speaker 1: exist in the same form anymore. It's been like melted
• 27:38
  Speaker 1: and reorganized. And so we have found life that's three
• 27:41
  Speaker 1: point five billion years old. Maybe there's life that's four
• 27:45
  Speaker 1: point six billion years old.
• 27:46
  Speaker 2: I doubt it.
• 27:47
  Speaker 1: That's the oldest Earth in the Solar System is, but
• 27:49
  Speaker 1: if it had shown up right, at the beginning, it
• 27:51
  Speaker 1: would have been just like obliterated and we wouldn't have
• 27:54
  Speaker 1: fossil evidence of it anymore.
• 27:56
  Speaker 4: But it's really important to understand this gap between when
• 27:59
  Speaker 4: the Earth formed and when life formed, because it's the
• 28:02
  Speaker 4: only piece of data we have to speculate about how
• 28:05
  Speaker 4: long it takes life to form, which is a big question.
• 28:08
  Speaker 3: Right.
• 28:08
  Speaker 4: If life forms like almost as soon as possible after
• 28:11
  Speaker 4: conditions are ready for it, that suggests with an equals
• 28:14
  Speaker 4: one that it forms off it when conditions are ready, right,
• 28:18
  Speaker 4: Whereas if it took like billions of years, that suggests
• 28:21
  Speaker 4: that it might take a long time on average, and
• 28:23
  Speaker 4: we shouldn't expect to find it everywhere. So it's like
• 28:26
  Speaker 4: super valuable piece of information.
• 28:28
  Speaker 5: Yeah, yeah, that's really interesting. But I feel like it
• 28:30
  Speaker 5: also depends on having gradients of temperature and water and
• 28:35
  Speaker 5: those conditions. I mean, if you got those right, you know,
• 28:38
  Speaker 5: maybe really just takes a much smaller amount of time. Yeah,
• 28:41
  Speaker 5: with those conditions, which we obviously are not going to
• 28:44
  Speaker 5: triangulate from evidence on Earth, but it's fun to think about.
• 28:48
  Speaker 2: Yeah, totally. But another nice thing about knowing about when life.
• 28:52
  Speaker 1: Popped up is that then you can try to figure
• 28:54
  Speaker 1: out what Earth was like at that time, so that
• 28:58
  Speaker 1: then you can say, Okay, what things were in the atmosphere,
• 29:02
  Speaker 1: what are like the starting materials that we're likely to have,
• 29:06
  Speaker 1: what's the temperature like? And this isn't I'll know this
• 29:08
  Speaker 1: isn't perfect because just because the Earth was an average
• 29:12
  Speaker 1: of I'm making a number up one hundred degrees fahrenheit
• 29:15
  Speaker 1: or something everywhere, there's still a ton of variability, right
• 29:18
  Speaker 1: depending on if you're at the bottom of the ocean
• 29:20
  Speaker 1: or something like that. And so it's helpful to know,
• 29:23
  Speaker 1: but it doesn't necessarily tell us everything we need to
• 29:26
  Speaker 1: know because there was a lot of variability depending on
• 29:28
  Speaker 1: where you are on the Earth. But now that I've
• 29:31
  Speaker 1: gone ahead and been like, we're going to tell you
• 29:33
  Speaker 1: what Earth is like, but it's not interesting because there
• 29:35
  Speaker 1: was variability, let's go ahead and talk about what Earth
• 29:39
  Speaker 1: was like about three and a half billion years old.
• 29:42
  Speaker 1: And we call this time period the Haydian, which is
• 29:46
  Speaker 1: like the hell like hot, nasty, hot, and nasty, which
• 29:49
  Speaker 1: Daniel's into, and so.
• 29:52
  Speaker 5: We could also call it like an auto cleave. Oh,
• 29:55
  Speaker 5: because you know, these days, if we want to sterilize something,
• 29:58
  Speaker 5: we put it in an autocla, which is hot and
• 30:01
  Speaker 5: high pressure, and I would call it extremely clean.
• 30:05
  Speaker 2: So you know, oh good, that's good. Maybe not great
• 30:08
  Speaker 2: for life, but clean is good.
• 30:11
  Speaker 5: Useful, yeah, useful, that's right.
• 30:13
  Speaker 4: Well.
• 30:13
  Speaker 1: So another thing is that the Sun back then was dimmer,
• 30:17
  Speaker 1: but because we didn't have an ozone layer, space radiation
• 30:21
  Speaker 1: UV radiation hit the surface a lot more often, which
• 30:25
  Speaker 1: probably also contributed to some of this sterilizing of the surface.
• 30:29
  Speaker 2: Like an autoclave, the.
• 30:30
  Speaker 1: Temperature and the atmospheric pressure were probably different than what
• 30:34
  Speaker 1: we experienced today, and partly that's because the atmosphere we
• 30:38
  Speaker 1: think was made of different stuff than we see now.
• 30:41
  Speaker 1: So eventually, when life came around, we started producing a
• 30:44
  Speaker 1: bunch of oxygen that got into the atmosphere, produced ozone, etc.
• 30:48
  Speaker 1: But we think that some of the starting materials in
• 30:50
  Speaker 1: Earth's atmosphere were things like carbon dioxide, methane, ammonia, and
• 30:55
  Speaker 1: water vapor, but again not a lot of oxygen, and.
• 30:59
  Speaker 3: This mostly came from volcanoes. Right.
• 31:00
  Speaker 4: We talked earlier about how Earth's first atmosphere, like most
• 31:04
  Speaker 4: of the universe and most of the Solar System, is
• 31:06
  Speaker 4: hydrogen and helium, but that was blown away because of
• 31:10
  Speaker 4: the Sun's radiation, and then we had a second atmosphere
• 31:13
  Speaker 4: which came from volcanic outgassing, and also you get like
• 31:16
  Speaker 4: bombardment from asteroids, and so some of the stuff on
• 31:19
  Speaker 4: those melt and that's where the second atmosphere comes from.
• 31:22
  Speaker 3: Cool.
• 31:22
  Speaker 2: Yeah, thank you for that.
• 31:23
  Speaker 1: And yeah, so the asteroids that you're talking about, a
• 31:26
  Speaker 1: lot of those fell during the Late Heavy Bombardment, which
• 31:29
  Speaker 1: was four point one to like three point eight billion
• 31:31
  Speaker 1: years ago, where we were just getting absolutely hammered.
• 31:34
  Speaker 4: Though it sounds like a battle in World War Two,
• 31:36
  Speaker 4: doesn't it.
• 31:37
  Speaker 2: It does, it does, but yeah, we got totally hammered.
• 31:40
  Speaker 1: And as I understand it, a lot of the craters
• 31:42
  Speaker 1: on the Moon are evidence of the Late Heavy bombardment
• 31:46
  Speaker 1: because our craters got sort of like eroded away over
• 31:48
  Speaker 1: time and you can't see them anymore, but there's evidence
• 31:51
  Speaker 1: on the Moon of them still.
• 31:53
  Speaker 4: Although I think that's suspect now because we only landed
• 31:55
  Speaker 4: in a small region on the Moon and that might
• 31:57
  Speaker 4: have been unrepresentative. So this we're seeing now about whether
• 32:00
  Speaker 4: the Late Heavy Bombardment was a real thing or not.
• 32:03
  Speaker 5: Really, I thought we knew a lot about the geography
• 32:07
  Speaker 5: of the Moon. We only know about the areas where
• 32:09
  Speaker 5: we landed.
• 32:10
  Speaker 4: We know a lot from observations, but we don't have
• 32:12
  Speaker 4: samples from a lot of the moon.
• 32:14
  Speaker 5: Oh I see.
• 32:14
  Speaker 4: Anyway, that's a whole other topic we can dig into
• 32:16
  Speaker 4: in another episode.
• 32:17
  Speaker 1: But yeah, well, but that's actually totally related to my
• 32:19
  Speaker 1: next point because now that we've laid out like, Okay,
• 32:22
  Speaker 1: this is what the early Earth was like, there are
• 32:24
  Speaker 1: other people you can talk to, other experts who are like, yes,
• 32:27
  Speaker 1: this story of what the early Earth was like has
• 32:30
  Speaker 1: become very popular, very well known. But actually there's a
• 32:33
  Speaker 1: lot of evidence that we can't be totally sure that
• 32:36
  Speaker 1: the early atmosphere had exactly the compounds that we were
• 32:40
  Speaker 1: talking about.
• 32:41
  Speaker 2: We could be wrong about a lot of this stuff,
• 32:43
  Speaker 2: and it could be that.
• 32:44
  Speaker 1: The early Earth wasn't super different than Earth today, except
• 32:48
  Speaker 1: that it definitely wouldn't have had as much oxygen in
• 32:50
  Speaker 1: the atmosphere because that's definitely a sign of life. But
• 32:53
  Speaker 1: so we're doing our best to guess what it was like,
• 32:56
  Speaker 1: you know, billions and billions of years ago. It's amazing
• 32:59
  Speaker 1: that we have anything to work from for something that's
• 33:02
  Speaker 1: that old.
• 33:03
  Speaker 2: But yeah, so I'm.
• 33:04
  Speaker 1: Waving my hands in the air a little bit what
• 33:06
  Speaker 1: I'm telling you about what Earth was like four billion
• 33:07
  Speaker 1: years ago, because this is just the best evidence that
• 33:10
  Speaker 1: we have right now.
• 33:11
  Speaker 4: And it's amazing that we know anything about what happened
• 33:13
  Speaker 4: billions of years ago, like what incredible detective work, right,
• 33:17
  Speaker 4: And as Hazel likes to say, science is like stuff happened,
• 33:20
  Speaker 4: and we're trying to figure out what.
• 33:24
  Speaker 1: Yes, that's that's totally that's a good depth, that's a
• 33:26
  Speaker 1: good explanation. Okay, So now that we have talked about
• 33:31
  Speaker 1: what early Earth was like, or now that we've admitted
• 33:33
  Speaker 1: that we're not totally sure, let's talk about how life arose.
• 33:38
  Speaker 1: And to figure out how life arose, we tend to
• 33:42
  Speaker 1: want to think about how certain things that we usually see.
• 33:46
  Speaker 2: In life popped up.
• 33:47
  Speaker 1: So, for example, lipids, these are things that are usually
• 33:51
  Speaker 1: used to make the cell membrane, so to like give
• 33:53
  Speaker 1: you a compartment that you can use to separate yourself
• 33:56
  Speaker 1: from the rest of the world. For example, carbohydrates. These
• 33:59
  Speaker 1: are like sugar and cellulose. They are delicious. Amino Acids
• 34:03
  Speaker 1: these are used to make up proteins and nucleic acids,
• 34:06
  Speaker 1: which are used to make up DNA and RNA, and
• 34:09
  Speaker 1: so a lot of the folks who study origins of
• 34:12
  Speaker 1: life are looking for conditions where you mix stuff together
• 34:16
  Speaker 1: that were likely to be together about three and a
• 34:20
  Speaker 1: half billion years ago or older, and then you wait
• 34:23
  Speaker 1: to see do any of these things pop up? And
• 34:27
  Speaker 1: so like what do you need to do to start
• 34:28
  Speaker 1: getting these But this is actually a pretty hard problem
• 34:32
  Speaker 1: to think about because like often to get one of
• 34:35
  Speaker 1: these things that we're talking about, you need others. So
• 34:38
  Speaker 1: for example, to get DNA or to copy DNA, that's
• 34:41
  Speaker 1: done with proteins. So what came first, the protein or
• 34:46
  Speaker 1: the DNA? And so trying to figure out how these
• 34:49
  Speaker 1: things pop up and work together and in what order
• 34:52
  Speaker 1: they show up is like a huge part of what
• 34:54
  Speaker 1: this field.
• 34:55
  Speaker 2: Is doing as I understand it, Yeah, one hundred percent.
• 34:58
  Speaker 5: I mean, most things that happen biology are possible without
• 35:02
  Speaker 5: the help of all of our fancy proteins and cellular machinery.
• 35:05
  Speaker 5: They're just very unlikely. They just take like a massive
• 35:09
  Speaker 5: amount of time and energy. The biology is just easing
• 35:12
  Speaker 5: the process and making it faster and more doable. So
• 35:16
  Speaker 5: if you were to give things a lot of time
• 35:18
  Speaker 5: and a couple of lightning strikes, for some energy. Then
• 35:22
  Speaker 5: that's the theory, is that a lot of these molecules
• 35:25
  Speaker 5: may have started to just form on their own without
• 35:27
  Speaker 5: any biology to guide them. And then maybe you're going
• 35:30
  Speaker 5: to get into the RNA world hypothesis, Kelly. But you know,
• 35:34
  Speaker 5: we don't have to debate between DNA and protein because
• 35:39
  Speaker 5: we have this intermediate molecule RNA revenucleic acids that are
• 35:44
  Speaker 5: able to do some of this chemistry that proteins are
• 35:47
  Speaker 5: good at, and also they can store information, so they're
• 35:50
  Speaker 5: kind of a jack of all trades of a molecule.
• 35:52
  Speaker 5: So we think that life probably started there.
• 35:55
  Speaker 4: But RNA doesn't have the same pr that DNA has,
• 35:57
  Speaker 4: Like fewer people know about it and seem to get
• 36:00
  Speaker 4: as much pressed.
• 36:01
  Speaker 5: Like does Starbucks put it in their coffees with the
• 36:04
  Speaker 5: big sign about protein shakes and stuff.
• 36:08
  Speaker 1: So Katrina was talking about ribozimes, right, Yeah, we're going
• 36:11
  Speaker 1: to jump into that a little bit more when we
• 36:13
  Speaker 1: come back, but I wanted to end this segment if
• 36:15
  Speaker 1: that's okay with aliens again, and so.
• 36:20
  Speaker 5: That was Daniel right up, Yeah, what Yeah.
• 36:23
  Speaker 1: Before we go to the break, let's real quick jump
• 36:26
  Speaker 1: into aliens again. And so there are some people who are,
• 36:28
  Speaker 1: you know, talking about like, well, how do you get
• 36:30
  Speaker 1: these four things with the conditions that we had here
• 36:33
  Speaker 1: on Earth four a billion years ago or something?
• 36:35
  Speaker 2: And there are.
• 36:35
  Speaker 1: Others that say, well, what if life just came here
• 36:40
  Speaker 1: from space? And this is the panspermia idea, where you know,
• 36:44
  Speaker 1: maybe life arose on Mars, something smashed into Mars and
• 36:47
  Speaker 1: that rock eventually lands on Earth and now Earth is
• 36:49
  Speaker 1: seated with life that started somewhere else.
• 36:52
  Speaker 4: What do you think, Daniel, I think that's a really
• 36:55
  Speaker 4: cool story, and it's really important to understand whether life
• 36:59
  Speaker 4: started on Earth or somewhere else because it changes how
• 37:03
  Speaker 4: we feel about ourselves and who we are.
• 37:05
  Speaker 3: And it's interesting.
• 37:07
  Speaker 4: But I don't think it's really relevant to this scientific
• 37:09
  Speaker 4: question of how life starts because it just sort of says, well,
• 37:13
  Speaker 4: maybe life started on Earth or maybe it started somewhere else.
• 37:15
  Speaker 4: It doesn't answer the question of how did it start.
• 37:18
  Speaker 4: It doesn't really matter to me if it started on
• 37:20
  Speaker 4: Mars and then landed here for the biological question of
• 37:24
  Speaker 4: how does life start. Of course, I'm curious about whether
• 37:27
  Speaker 4: we're all secretly Martians, But you know, it sort of
• 37:30
  Speaker 4: seems to me like kicking the question down the road
• 37:32
  Speaker 4: instead of answering it.
• 37:33
  Speaker 5: Yeah, it also impacts how often these things happen, though,
• 37:37
  Speaker 5: getting back to understanding the initial conditions, I mean, if
• 37:41
  Speaker 5: the conditions are so rare that it really only happened
• 37:43
  Speaker 5: once somewhere in the universe, not even on Earth, that
• 37:47
  Speaker 5: makes it seem even harder.
• 37:49
  Speaker 3: Yeah.
• 37:49
  Speaker 4: And I think we have no evidence at all really
• 37:52
  Speaker 4: for like pant spermia, especially directed panspermia as some like
• 37:57
  Speaker 4: professor from Harvard likes to talk about, or stellar visitors
• 38:01
  Speaker 4: maybe being like alien capsules containing seeds of life. Like,
• 38:04
  Speaker 4: there's no evidence for that, And if anybody was gonna
• 38:07
  Speaker 4: be excited about that, it would be me. So the
• 38:09
  Speaker 4: fact that I'm being skeptical about I should tell you something.
• 38:13
  Speaker 1: Daniel's never an alien's wet blanket, but in this case
• 38:17
  Speaker 1: he is. So that's all you need to know.
• 38:18
  Speaker 3: Follow the data.
• 38:20
  Speaker 2: All right, let's.
• 38:20
  Speaker 1: Take a break, and when we get back, we'll talk
• 38:22
  Speaker 1: about the miller Uri experiment and whether metabolism or RNA
• 38:27
  Speaker 1: came first.
• 38:47
  Speaker 2: All Right, we're back. Do you too.
• 38:50
  Speaker 1: Remember learning about the miller Uri experiment when you were
• 38:53
  Speaker 1: in school?
• 38:53
  Speaker 5: Definitely?
• 38:54
  Speaker 4: Yeah, They had like a flask of some stuff, and
• 38:57
  Speaker 4: they sapped it and it turned into more interesting lifelife stuff.
• 39:00
  Speaker 3: Is that right?
• 39:00
  Speaker 1: Yeah, I don't need to explain it. I mean, that's
• 39:05
  Speaker 1: almost exactly what my notes have like. I mean, in particular,
• 39:08
  Speaker 1: they had ammonia, methane, and hydrogen, so they had stuff
• 39:12
  Speaker 1: that they thought was present on early Earth. Actually, they
• 39:14
  Speaker 1: were using Jupiter's atmosphere as sort of a proxy for
• 39:18
  Speaker 1: what they thought early Earth was like, which we no
• 39:20
  Speaker 1: longer necessarily think was the right thing to be working with.
• 39:23
  Speaker 1: But anyway, then they zapped it with some electricity to
• 39:27
  Speaker 1: simulate lightning strikes, and they ended up getting some amino acids.
• 39:32
  Speaker 1: But one of the problems is that we no longer
• 39:34
  Speaker 1: necessarily think that the world they created in this flask
• 39:38
  Speaker 1: is necessarily like what we thought early Earth.
• 39:40
  Speaker 2: Was going to be like.
• 39:41
  Speaker 1: But it did show that, like, you throw some stuff
• 39:44
  Speaker 1: together that isn't life, and you start getting the building
• 39:46
  Speaker 1: blocks of life out of it, which is pretty darn exciting.
• 39:51
  Speaker 1: And since we've done a bunch of experiments where we've
• 39:53
  Speaker 1: sort of updated the gases that are in there, the
• 39:55
  Speaker 1: sources of energy that are being input into the system,
• 39:58
  Speaker 1: and surprisingly pretty all you do still get like things
• 40:02
  Speaker 1: that look like the building blocks of life popping up,
• 40:05
  Speaker 1: and so getting things like amino acids just sort of
• 40:09
  Speaker 1: randomly in the environment doesn't actually seem like it's that hard.
• 40:14
  Speaker 1: And so then the question is how do you go
• 40:15
  Speaker 1: from there to something that you know responds to Darwinian
• 40:18
  Speaker 1: evolution or something like that. And so the question there
• 40:21
  Speaker 1: is do you start with metabolism, so the ability to
• 40:25
  Speaker 1: do like chemical reactions that give yourself energy so that
• 40:28
  Speaker 1: then you can do other stuff. And I've probably done
• 40:31
  Speaker 1: a really bad job of defining metabolism because it still
• 40:33
  Speaker 1: kind of blows my mind. So I'm gonna throw to
• 40:35
  Speaker 1: Katrina in a second. And then the other hypothesis is
• 40:37
  Speaker 1: the RNA world that maybe you started with RNA first,
• 40:40
  Speaker 1: and then from RNA you sort of structure things together
• 40:44
  Speaker 1: and then start using metabolism to build things that are
• 40:46
  Speaker 1: more complicated.
• 40:47
  Speaker 2: So Katrina go, I don't even really know.
• 40:51
  Speaker 1: This is where I start to feel overwhelmed, because this
• 40:53
  Speaker 1: is where it becomes a lot of biochemistry.
• 40:56
  Speaker 5: Yeah, well, metabolism as a word I find fascinating. And
• 41:00
  Speaker 5: when I get asked that question when I'm over at
• 41:03
  Speaker 5: the Integrative Health Center and the teaching kitchen and people
• 41:06
  Speaker 5: ask me about metabolism. They're asking, you know, how can
• 41:10
  Speaker 5: I boost my metabolic rate? So I can, you know,
• 41:14
  Speaker 5: lose weight and eat lots of delicious things, and which
• 41:19
  Speaker 5: is a good goal. But for you know, what we're
• 41:21
  Speaker 5: talking about for life is the chemistry of getting energy
• 41:24
  Speaker 5: and using that energy. So yeah, it's really interesting to
• 41:29
  Speaker 5: think about that in the context of early life. I
• 41:31
  Speaker 5: think it gets back to some of the seclusion and
• 41:33
  Speaker 5: compartmentalization definitions that you were bringing up earlier, because everything
• 41:38
  Speaker 5: runs on gradients, and so building up differences in concentration
• 41:43
  Speaker 5: of molecules against a membrane of some kind is a
• 41:47
  Speaker 5: way to store energy and to use energy to propel
• 41:50
  Speaker 5: your processes forward. So in my mind, metabolism comes down
• 41:55
  Speaker 5: to being able to organize systems for obtaining energy and
• 42:00
  Speaker 5: using chemicals to do that.
• 42:03
  Speaker 4: So let me see, if I understand from a physics
• 42:05
  Speaker 4: point of view, you're saying that we're looking for a
• 42:08
  Speaker 4: process that we see a lot in life, which is
• 42:11
  Speaker 4: use of energy to run yourself, and that we do
• 42:14
  Speaker 4: this chemically by storing stuff upgradients, which sounds complicated, but
• 42:18
  Speaker 4: it's basically like if you carried a bunch of rocks
• 42:21
  Speaker 4: up a hill and left them at the top of
• 42:22
  Speaker 4: the hill. That would have stored energy in it which
• 42:25
  Speaker 4: you could release when you wanted to by rolling them
• 42:27
  Speaker 4: down the hill. And then the rock gets all this
• 42:29
  Speaker 4: speed which you could then use to like you spin
• 42:32
  Speaker 4: a wheel and grind your.
• 42:33
  Speaker 3: Flower or something.
• 42:34
  Speaker 5: Exactly. Yeah, that's a really good analogy. I like that
• 42:36
  Speaker 5: a lot. But yeah, it's exactly. It's like pushing chemical
• 42:40
  Speaker 5: molecules onto one side of a barrier and then that
• 42:44
  Speaker 5: stores energy.
• 42:46
  Speaker 1: I'm going to do my best to summarize one hypothesis
• 42:51
  Speaker 1: for how life could have started around hydrothermal vents. But
• 42:54
  Speaker 1: I'm gonna preface this by saying this is pretty chemistry heavy,
• 42:58
  Speaker 1: which we all know how I feel about that. Okay,
• 43:01
  Speaker 1: So here's here's one idea for how life could have started. So,
• 43:03
  Speaker 1: if you are at a hydrothermal vent, the stuff that's
• 43:06
  Speaker 1: getting pushed out of the vent is at a very
• 43:09
  Speaker 1: different pH than the water outside of the vent, and
• 43:13
  Speaker 1: so this is a gradient that can be used to
• 43:15
  Speaker 1: generate energy. And so at these hydrothermal vents, you've got
• 43:18
  Speaker 1: this energy source. These hydrothermal vents also have rocks that
• 43:23
  Speaker 1: tend to be sort of sponge shaped, and if you
• 43:25
  Speaker 1: look at a sponge, there's like all of these little
• 43:27
  Speaker 1: sort of like pores and holes in it, and each
• 43:30
  Speaker 1: one of those pores or holes could have acted sort
• 43:33
  Speaker 1: of like a cell membrane, sort of separating into compartments,
• 43:37
  Speaker 1: so that stuff could happen in each of those different compartments.
• 43:40
  Speaker 1: And so now you have like primitive compartments, and you
• 43:43
  Speaker 1: have a source of energy, and some of the minerals
• 43:46
  Speaker 1: in that area can be used to catalyze reactions. And
• 43:49
  Speaker 1: when I say used to catalyze reactions, I'm not even
• 43:52
  Speaker 1: totally sure I know what that means. But anyway, so
• 43:55
  Speaker 1: hydrothermal vents are supposed to have all of these different
• 43:59
  Speaker 1: features where you can imagine metabolism arising first, and then
• 44:04
  Speaker 1: you're able to, through some other kind of chemistry magic,
• 44:08
  Speaker 1: get RNA and the ball gets rolling. And for anyone
• 44:10
  Speaker 1: who wants a really great book on it by a
• 44:12
  Speaker 1: chemist who knows what he's talking about, check out Nick
• 44:14
  Speaker 1: Layane's book The Vital Question, which is all about the
• 44:17
  Speaker 1: metabolism first hypothesis. What do you think did that make
• 44:21
  Speaker 1: any sense?
• 44:21
  Speaker 2: Katrina?
• 44:22
  Speaker 5: Yeah, very much so. I mean, I really like that
• 44:26
  Speaker 5: idea of almost like a life rock hybrid scenario where
• 44:31
  Speaker 5: the shapes of all those porous rocks around the hydrothermal
• 44:35
  Speaker 5: events are providing some of the structure that modern cells provide,
• 44:39
  Speaker 5: and so they could just kind of borrow that, and
• 44:42
  Speaker 5: you know, I could imagine like little seals of lipids
• 44:47
  Speaker 5: forming at the surface of a little pore, and then
• 44:50
  Speaker 5: that's almost like a little prototype for a cell where
• 44:53
  Speaker 5: you could get concentrated organic molecules on one side or
• 44:57
  Speaker 5: the other. And yeah, I really love thinking about that.
• 45:00
  Speaker 5: There's so much room for heterogeneity and diversity in that environment.
• 45:04
  Speaker 1: Yeah, And is it going to be ironic if, like,
• 45:07
  Speaker 1: down the road it turns out that this worked, and
• 45:09
  Speaker 1: like life depended on rocks and all the time we're
• 45:12
  Speaker 1: like you go from a gradient of rocks to life.
• 45:15
  Speaker 1: It's like the rocks would be like, you really didn't
• 45:17
  Speaker 1: appreciate us, so you couldn't be here without us totally.
• 45:19
  Speaker 5: Yeah, they're not just this like impartial, inert bystander. They
• 45:23
  Speaker 5: were like important.
• 45:25
  Speaker 4: Yeah, So you're saying essentially that, like you're building a
• 45:28
  Speaker 4: little chemical engine here, something that's taking advantage of energy
• 45:32
  Speaker 4: to do something there's no like genome, there's no heredity.
• 45:37
  Speaker 4: You just have like little bags of stuff that have
• 45:40
  Speaker 4: an energy source and some kind of driving reaction and
• 45:44
  Speaker 4: it's being contained by these little rocks. And you know,
• 45:48
  Speaker 4: if we found just that on an alien planet, would
• 45:50
  Speaker 4: you call that life?
• 45:52
  Speaker 3: No?
• 45:52
  Speaker 1: And I don't think that the people who study origins
• 45:55
  Speaker 1: of life would call that life either. But I think
• 45:58
  Speaker 1: that they would argue that this is a first step.
• 46:01
  Speaker 1: And I should say that there are like many, many,
• 46:04
  Speaker 1: many different hypotheses for where this stuff started. Maybe it's
• 46:07
  Speaker 1: not hydrothermal vents. Maybe it's hot spring somewhere. And maybe
• 46:10
  Speaker 1: it's not the white smokers, it's the black smokers, because
• 46:13
  Speaker 1: there's different kinds of hydrothermal vents. I've been talking about
• 46:15
  Speaker 1: a very early step for one hypothesis, but there's a
• 46:21
  Speaker 1: ton of different other ideas, And I suspect the people
• 46:23
  Speaker 1: who study the idea that I tried to summarize would say, yeah,
• 46:28
  Speaker 1: and then we have like a whole different set of
• 46:30
  Speaker 1: hypotheses for what happens next.
• 46:32
  Speaker 2: But first we're just trying to get this one step going.
• 46:35
  Speaker 1: And what's kind of amazing is that by creating these
• 46:38
  Speaker 1: very specific hypotheses. They've created scenarios that they can recreate
• 46:42
  Speaker 1: in the lab, and they do a bunch of these experiments.
• 46:45
  Speaker 1: They're actually trying to you know, create the origin of
• 46:48
  Speaker 1: life in the lab or you know, simulate the conditions
• 46:51
  Speaker 1: under which life started in the lab, and then they
• 46:53
  Speaker 1: go out in the field and they try to see, well,
• 46:55
  Speaker 1: are we seeing similar things happening in the field. So
• 46:57
  Speaker 1: this isn't just a philosophical debate, although the ophical debate
• 47:00
  Speaker 1: part is amazing. This is actually like there's experiments going
• 47:04
  Speaker 1: on where, you know, year after year we're sort of
• 47:06
  Speaker 1: whittling away at which one of these options that we
• 47:08
  Speaker 1: talk about are feasible and which ones aren't. So we're actually,
• 47:11
  Speaker 1: you know, we're making progress. It's chemistry progress. So it's
• 47:15
  Speaker 1: hard to share exactly what's happening, but people are working
• 47:19
  Speaker 1: on it. And then there's the RNA world hypothesis. Katrida,
• 47:23
  Speaker 1: could you go into a little bit more detail about ribozymes,
• 47:26
  Speaker 1: which are amazing because they both store genetic information and
• 47:29
  Speaker 1: replicate themselves, which we used to think you needed proteins for.
• 47:32
  Speaker 5: Yeah, exactly, so, and you know, in my mind, this
• 47:35
  Speaker 5: hypothesis about the RNA world goes hand in hand with
• 47:38
  Speaker 5: the metabolism first thinking, because you're gonna need energy in
• 47:41
  Speaker 5: those building blocks of life to build up the kinds
• 47:45
  Speaker 5: of polymers that have been so important for the basis
• 47:48
  Speaker 5: of life. But RNA ribon nucleic acids are very similar
• 47:52
  Speaker 5: to DNA. Just one of the important building blocks, the
• 47:56
  Speaker 5: ribonucleic acid molecule itself has an additional oxygen, and so
• 48:02
  Speaker 5: RNA molecules are inherently both more unstable but also more
• 48:08
  Speaker 5: creative and capable of interesting kinds of catalysis. And so
• 48:12
  Speaker 5: when you build a chain of RNA molecules, they have
• 48:16
  Speaker 5: the capacity to fold over on themselves and build structures
• 48:21
  Speaker 5: that you can use to do the same kind of
• 48:23
  Speaker 5: projects that proteins do. So the chains of RNA that
• 48:27
  Speaker 5: build themselves up into a little macromolecule called a ribozyme,
• 48:33
  Speaker 5: they are capable of some of the same chemistry that
• 48:35
  Speaker 5: proteins can do. So what proteins do is they go
• 48:39
  Speaker 5: grab a couple of substrates that they want to put
• 48:42
  Speaker 5: together into a reaction, and they hold them in a
• 48:44
  Speaker 5: position that makes it favorable for that reaction to happen.
• 48:48
  Speaker 5: And so ribeozins can do that too. They can build
• 48:51
  Speaker 5: a little structure and then they can grab onto molecules
• 48:54
  Speaker 5: in their environment and put the two substrates near each
• 48:58
  Speaker 5: other and like let the magic happen. So that's it's
• 49:00
  Speaker 5: really all they're doing. They're not like forcing the reaction,
• 49:02
  Speaker 5: they're just making it way more likely. And so ribozymes
• 49:06
  Speaker 5: are chains of RNA. There's still a big part of
• 49:09
  Speaker 5: the molecular central dogma of how molecular biology works in
• 49:13
  Speaker 5: our current modern cells. But in those days we probably
• 49:16
  Speaker 5: didn't have DNA or prouteins yet, we only had RNA.
• 49:20
  Speaker 5: So that's the RNA world hypothesis was that the first
• 49:22
  Speaker 5: molecules to form were chains of RNA that can store
• 49:27
  Speaker 5: energy just like DNA. They're very The molecules that comprise
• 49:31
  Speaker 5: RNA are super similar to DNA. There's just one extra
• 49:33
  Speaker 5: hydroxyl group. But then because of that extra hydroxyl group,
• 49:37
  Speaker 5: they have more capacity for catalysis. They're not as good
• 49:40
  Speaker 5: for storing genetic information because they break more easily that
• 49:44
  Speaker 5: oxygen makes them less stable.
• 49:46
  Speaker 2: Huh.
• 49:47
  Speaker 1: I didn't know most of that, which probably means I
• 49:49
  Speaker 1: slept through a really important lecture.
• 49:51
  Speaker 2: But that's amazing.
• 49:54
  Speaker 5: It's such a good story. Yeah, I love getting to
• 49:56
  Speaker 5: tell that one to students because it's like so apparent
• 49:58
  Speaker 5: to just look at that joxile hanging off the ribos
• 50:01
  Speaker 5: and you're like, look at all the stuff that made happen,
• 50:04
  Speaker 5: you know, mm hm.
• 50:05
  Speaker 1: So you're clearly team RNA in the RNA versus DNA debate.
• 50:10
  Speaker 5: I mean, I would not give up my DNA. Man
• 50:13
  Speaker 5: DNA is like rile, yeah, but I mean.
• 50:15
  Speaker 1: But you did have a sparkle in your eye when
• 50:17
  Speaker 1: you were talking about the RNA.
• 50:19
  Speaker 5: But yeah, I think it's fun to imagine that world
• 50:22
  Speaker 5: before we had the DNA or the protein, and I
• 50:25
  Speaker 5: think it's cool that we understand why. But when it
• 50:28
  Speaker 5: comes down to it, you know, I trust my DNA.
• 50:33
  Speaker 1: Okay, So you know this is a Daniel and Kelly's
• 50:36
  Speaker 1: Extraordinary Universe episode. So we talked a lot about what
• 50:39
  Speaker 1: we don't know and sort of the limits of our knowledge.
• 50:43
  Speaker 1: But I am still super excited about how far we've gotten,
• 50:47
  Speaker 1: like how many different conditions we've considered in the lab
• 50:50
  Speaker 1: and in the field, and how we've seen the building
• 50:53
  Speaker 1: blocks of life showing up in these different sorts of environments.
• 50:56
  Speaker 1: I mean, there have been papers that I read where
• 50:57
  Speaker 1: like something had to happen in the ocean, and it
• 51:00
  Speaker 1: got thrown up on top of the land, and then
• 51:02
  Speaker 1: it dried, and the drying was important for a step,
• 51:04
  Speaker 1: and then it gets washed back into the ocean, and
• 51:06
  Speaker 1: that's important for the next step. And they've simulated all
• 51:08
  Speaker 1: of this stuff in the lab.
• 51:09
  Speaker 2: Amazing, totally amazing.
• 51:11
  Speaker 1: But of course, the more steps that are involved, the
• 51:13
  Speaker 1: more complicated it probably is for life to arise. And
• 51:16
  Speaker 1: one of the questions that really stuck with me while
• 51:19
  Speaker 1: I was doing this reading was, you know, in situation
• 51:22
  Speaker 1: after situation, it seems like we were figuring out how
• 51:25
  Speaker 1: to come up with the building blocks of life, which
• 51:28
  Speaker 1: makes it surprising to me that we don't see life
• 51:31
  Speaker 1: popping up more often. And I guess the point is that,
• 51:35
  Speaker 1: you know, if you're talking about it, you know, first
• 51:36
  Speaker 1: it happens in the ocean, then it gets washed up
• 51:38
  Speaker 1: on a volcano bank, and then it has to you know,
• 51:40
  Speaker 1: fall back in. There's a lot of steps, and it's
• 51:42
  Speaker 1: super complicated, but it's kind of amazing that this thing
• 51:45
  Speaker 1: may have only happened and then really taken off once
• 51:49
  Speaker 1: and now here we all are and I don't really
• 51:52
  Speaker 1: know where I'm going with this. But I had a
• 51:54
  Speaker 1: lot of fun researching this, even though there's a lot
• 51:56
  Speaker 1: of chemistry.
• 51:58
  Speaker 4: And I'm really fascinating this question of like how often
• 52:00
  Speaker 4: did it happen? Like it's true that there's a lot
• 52:03
  Speaker 4: of evidence that all life on Earth has a single
• 52:06
  Speaker 4: common ancestor, but I'm not sure that rules out an
• 52:09
  Speaker 4: independent strain of life developing and then getting squashed by
• 52:13
  Speaker 4: or out competed.
• 52:14
  Speaker 1: Right, Yeah, And that was a point that I saw
• 52:17
  Speaker 1: made in these articles over and over again, is that
• 52:19
  Speaker 1: what we see is the one instance where life sort
• 52:22
  Speaker 1: of really got going and then stuck around and diversified.
• 52:25
  Speaker 1: But then to me, there's this other question of are
• 52:28
  Speaker 1: the conditions so different now that it just could never
• 52:31
  Speaker 1: happen again?
• 52:32
  Speaker 2: Like why does life not start fresh now?
• 52:36
  Speaker 1: And maybe it is something about the Earth being so different,
• 52:39
  Speaker 1: our conditions being so different now that you just couldn't
• 52:41
  Speaker 1: get it happening again.
• 52:42
  Speaker 2: But it makes me feel pretty lucky to be here.
• 52:45
  Speaker 5: I think. Yeah, I also thought about that a lot.
• 52:48
  Speaker 5: I think that the oxygen in the atmosphere I'm sure
• 52:50
  Speaker 5: you read all about this, is a major reason that
• 52:53
  Speaker 5: it's harder for these delicate initial life forms that were
• 52:57
  Speaker 5: probably emerging three and a half billion years ago. You know,
• 53:00
  Speaker 5: those guys could not stand the site of a molecule
• 53:03
  Speaker 5: of oxygen. It would immediately croak. So I think our
• 53:06
  Speaker 5: current conditions make that harder. But you know, it could
• 53:08
  Speaker 5: be that down in the deep sea thermal vents, those
• 53:11
  Speaker 5: conditions are still ripe for new origins, and so it
• 53:16
  Speaker 5: could be that some of those initial steps are happening.
• 53:19
  Speaker 5: They might not make it that far these days because
• 53:21
  Speaker 5: there's so much competition, but I would not be surprised
• 53:24
  Speaker 5: if there are places where those conditions still exist on Earth.
• 53:28
  Speaker 1: And check out our interview with doctor Andrew David Thayler
• 53:31
  Speaker 1: where he's talking about what's happening at hydrothermal events and
• 53:34
  Speaker 1: why we might want to be careful about mining them,
• 53:36
  Speaker 1: because this could be these vents could be a really
• 53:39
  Speaker 1: great place for us to be studying the origins of
• 53:41
  Speaker 1: life and trying to see if you know, maybe it
• 53:43
  Speaker 1: could ever happen again. But if we mind the heck
• 53:45
  Speaker 1: out of them and destroy them, we'd lose the ability
• 53:48
  Speaker 1: to study them.
• 53:49
  Speaker 4: Well, we don't know, but I suspect the origins of
• 53:51
  Speaker 4: life are hot and nasty and not very boring. Thanks
• 54:02
  Speaker 4: everybody for listening. Please go and do us a favor
• 54:04
  Speaker 4: and rate the show on.
• 54:05
  Speaker 3: Whatever podcast app you're using. It really helps people find us.
• 54:09
  Speaker 1: Daniel and Kelly's Extraordinary Universe is edited by the amazing
• 54:13
  Speaker 1: Matt Kesselman.
• 54:14
  Speaker 4: He really is a wizard. You can also find us
• 54:17
  Speaker 4: online on Blue Sky, Instagram, and x D and K Universe.
• 54:23
  Speaker 4: Come engage with us.
• 54:24
  Speaker 1: You can email us at questions at Danielankelly dot org.
• 54:28
  Speaker 1: We really do want to hear.
• 54:29
  Speaker 4: From you, and you can find our website www dot
• 54:32
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• 54:36
  Speaker 4: to join our discord where everybody comes and talks about
• 54:39
  Speaker 4: the amazing universe.
• 54:41
  Speaker 1: And we also have the most amazing moderators. This is
• 54:45
  Speaker 1: an iHeart podcast. Thanks for joining us.